This invention relates to a improved alignment coupling and method for joining an extensible member to an actuated member providing a floating alignment and easy assembly of the simplified components within a receptacle having a receiving passageway in the actuated member.
The prior art is represented by U.S. Pat. No. 5,135,329 directed to an alignment coupler for use with a pneumatic linear actuator wherein a piston rod is secured to a coupler which is in turn fastened to an actuated member for moving an external load. The coupler is fastened to a threaded member having a conical surface carried in a tapered bore for permitting axial adjustment. Radial adjustment is provided by a flange on the coupler body which is slidably carried within high density polyethylene rings within a chamber. Since the piston rod must be attached through the coupler which in turn has a threaded member projecting therethrough for attachment to the actuated member, a separate thickness of material is required to accommodate the conical threaded member to permit axial adjustment. The patent further typifies the prior art in that assembly is complicated, requiring a number of separate precision-made parts which must be assembled and confined within a cylindrical seat as by a snap ring which is carried in a groove machined in the cylindrical wall of the seat. The prior art is further exemplified by U.S. Pat. Nos. 5,113,746, 5,440,971, 5,560,729 and 5,634,486.
Another prior art device utilizes a coupler with an intermediate circumferential groove creating a dumbbell-like shape. A U-shaped slot in an actuated member defines a web received within the groove. A very close tolerance must be achieved, otherwise a tapping action results from excessive backlash between the two members when the cylinder is cycled.
Since linear actuators such as pneumatic actuators of the prior art must be capable of use for millions of cycles, alignment of the piston rods with associated components is of paramount importance. Any substantial misalignment results in excessive wear, destroying the useful life of the linear actuator. Loose connections and noisy operation are additional disadvantages common to the prior art.